AZ-305 Design data storage solutions Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Use the hot tier for all data to ensure high performance.

  Why it's wrong here

  Using the hot tier for all data is misguided because hot tier carries the highest per-GB storage price among Azure Blob Storage access tiers, even though it offers negligible latency or throughput advantage for data that is rarely touched. For archival datasets, the extra spend does not buy meaningful performance; instead, it inflates the storage bill without addressing the actual need, which is low-cost long-term retention. Performance benefits of hot tier only matter for frequently accessed data, so applying it indiscriminately ignores the cost structure Azure designed.

• ✓

  Consider early deletion penalties for data moved to archive tier.

  Why this is correct

  The archive access tier in Azure Blob Storage carries a 180-day minimum billing period; if you delete a blob or move it to a hotter tier before 180 days, you are charged an early deletion fee equal to the remaining days of storage. This penalty exists because Microsoft prices archive storage on the assumption of long-term commitment, and the fee can easily erase any savings from tiering data down. Therefore, any lifecycle policy that archives data must include a retention analysis to avoid unexpected charges when data is retired prematurely.

• ✓

  Account for data retrieval (rehydration) costs when accessing archived data.

  Why this is correct

  Reading an archived blob requires a rehydration operation to first move the blob to the hot or cool tier, and this process incurs both a per-GB retrieval cost and a time delay that can range from one to fifteen hours depending on the rehydration priority. In addition, you pay for the rehydration data transfer and any subsequent read operations, so the total cost of accessing archived data is substantially higher than its storage cost alone. If your compliance or business process anticipates periodic retrieval of old data, you must budget for these rehydration expenses or choose a more suitable tier, such as cool.

• ✓

  Choose the appropriate access tier (hot, cool, or archive) based on access frequency.

  Why this is correct

  Azure Blob Storage offers hot, cool, cold, and archive tiers, each optimized for a different access frequency pattern, and matching the tier to how often data is read is the core of cost-effective storage design. Hot tier suits frequently accessed data, cool tier suits data not accessed for 30 days or more, and archive tier suits data that is rarely accessed and tolerated a long retrieval latency. Setting the incorrect tier for a dataset means either overpaying for storage in a hotter tier or facing high retrieval/early-deletion costs in a colder tier, so the access frequency must drive the tier selection and be supported by life-cycle management rules.

• ✗

  Use geo-redundant storage (GRS) for all archive data.

  Why it's wrong here

  Geo-redundant storage (GRS) as a default for all archive data is wasteful because GRS incurs substantial additional costs for synchronous replication to a paired secondary region, and most archival data does not require regional failover or multi-region durability. Archive data often exists for compliance, legal, or historical purposes where local or zone-redundant storage (LRS or ZRS) is sufficient, or where the data can be regenerated from an on-premises copy if the primary region fails. Additionally, GRS archive tiers only offer redundant copies in the secondary region but do not provide read access to that copy unless you use RA-GRS, so you may pay for replication features you never actually use.

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